Gamma Velorum, also called Suhail, is a favorite multiple-star system among professional astronomers, who sometimes call it the “spectral gem of the southern skies”. This is a six-star system, and the brightest of the stars is losing mass at a rapid rate, an effect which causes the strange spectral signature. This deep-southern star has a modern name, too, which commemorates a brave spacefarer who sadly never got off the ground…
Gamma Velorum shines at magnitude 1.7. The primary star consists of two unresolvable stars. One is a massive evolved star — a Wolf-Rayet star — that’s shedding mass at a rapid rate. A few million years ago, the star had a mass of 40 suns. Today, it’s slimmed down to “only” 10 solar masses. The escaping hot gas causes the curious spectral signature of this star. This massive star has a close, massive blue O-type companion that revolves around the Wolf-Rayet star once every 79 days.
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About 41″ to the south-southwest lies a 4th-magnitude blue-white star that’s easily resolved in binoculars or small telescope at low power. Recent surveys by the Hipparchos satellite revealed this star is not physically associated with its brighter neighbor. Another 8.5-magnitude companion is visible 62.3” away from the primary. A second double star is located 94” away from the primary. This double is split by just 1.8” and has components with magnitude 9.4 and 13.5.
Gamma Velorum lies 530 light years away. It’s visible only south of 35°N latitude.
The name of the star, Suhail, causes some confusion because the star lambda Velorum is also called Suhail. But gamma Velorum also has a more modern name. It was coined by astronaut Virgil (Gus) Grissom, the commander of the first Apollo mission. The crew of Apollo 1 planned to use gamma Velorum to help navigate their spacecraft. Grissom jokingly called the star “Regor”, after his crewmate Roger Chaffee (Regor is Roger spelled backwards). After the ghastly accidental fire that claimed the lives of Grissom, Chaffee and their fellow astronaut Edward White on January 27, 1967, the name Regor was informally adopted as the name of this fascinating star system.
Bonus Object: Turn your gaze just 1 degree south of Regor to see the fine T-shaped open cluster NGC 2547. The shape is visible in binoculars, and the cluster opens up nicely in a small telescope. NGC 2547 is sometimes called “St. Peter’s Cross”.